VarstepCondExpression Class Reference

Represents XQuery condition if($x) or if($x/bib/book). More...

#include <varstepcondexpression.h>

Inheritance diagram for VarstepCondExpression:

Collaboration diagram for VarstepCondExpression:

List of all members.

Public Member Functions

VarstepCondExpression (VarExpression *_var)

Constructor.

VarstepCondExpression (VarStepExpression *_varstep)

Constructor.

virtual ~VarstepCondExpression ()

virtual void scopeCheck (vector< unsigned > &def_vars, vector< unsigned > &introduced_vars, vector< unsigned > &violating_vars)

virtual void replaceVarId (unsigned old_id, unsigned new_id)

virtual void extractDependencies (vector< DependencySet * > *depset)

void rewriteVarstepCondExps ()

virtual void print (OutputStream &dos) const

virtual void init (BufferNode *root)

virtual bool evalCond (OutputStream &eos, Environment *env, unsigned modus)

Private Attributes

VarExpression * var

The entered VarExpression.

VarStepExpression * varstep

The entered VarStepExpression.

ExistsCondExpression * econd

The rewritten ExistsCondExpression of the entered VarExpression or VarStepExpression.

Detailed Description

Represents XQuery condition if($x) or if($x/bib/book).

Represents XQuery condition if($x) or if($x/bib/book), which takes either a VarExpression, e.g. if($x), or a VarStepExpression, e.g. if($x/bib/book) or if(/bib//book) respectively, as argument and returns true if the sequence located through the entered VarExpression or the entered VarStepExpression respectively contains one or more items, false otherwise.

Note:: This expression does not exists instead it is rewritten to fn:exists.

Author:: Michael Schmidt
Gunnar Jehl

Version:: 2.1

License:: Software License Agreement (BSD License)

Definition at line 56 of file varstepcondexpression.h.

Constructor & Destructor Documentation

VarstepCondExpression::VarstepCondExpression ( VarExpression * _var )

Constructor.

Constructor - creating object for a VarExpression.

Parameters:

[in] _var Pointer to a VarExpression object.

Definition at line 37 of file varstepcondexpression.cpp.

VarstepCondExpression::VarstepCondExpression ( VarStepExpression * _varstep )

Constructor.

Constructor - creating object for a VarStepExpression.

Parameters:

[in] _varstep Pointer to a VarStepExpression object.

Definition at line 41 of file varstepcondexpression.cpp.

VarstepCondExpression::~VarstepCondExpression ( ) [virtual]

Destructor.

Definition at line 45 of file varstepcondexpression.cpp.

References econd.

Member Function Documentation

bool VarstepCondExpression::evalCond	(	OutputStream &	eos,
		Environment *	env,
		unsigned	modus
	)			`[virtual]`

Evaluates the corresponding CondExpression.

Parameters:

`[in]`	eos	Pointer to a OutputStream object.
`[in]`	env	Pointer to a Environment object.
`[in]`	modus	Evaluation modus.

Return values:

bool true if the corresponding CondExpression is true, false otherwise.

Exceptions:

RuntimeException

If illegal evaluation mode (argument: unsigned modus).

Implements CondExpression.

Definition at line 92 of file varstepcondexpression.cpp.

References econd, and ExistsCondExpression::evalCond().

void VarstepCondExpression::extractDependencies ( vector< DependencySet * > * depset ) [virtual]

Extracts the needed dependencies of a query.

Extracts the needed dependencies of a query, which are needed for constructing the ProjectionTree.

Parameters:

[in,out] depset Pointer to a vector containing Pointer to DependencySet objects.

Return values:

void

Reimplemented from Expression.

Definition at line 67 of file varstepcondexpression.cpp.

References econd, and ExistsCondExpression::extractDependencies().

void VarstepCondExpression::init ( BufferNode * root ) [virtual]

Initializes the query for evaluation.

Initializes the query for evaluation. Up to now only all required BufferIterator objects are created to speed up query evaluation.

Parameters:

[in] root Pointer to a BufferNode object.

Return values:

void

Reimplemented from Expression.

Definition at line 88 of file varstepcondexpression.cpp.

References econd, and ExistsCondExpression::init().

void VarstepCondExpression::print ( OutputStream & dos ) const [virtual]

Prints the expression.

Parameters:

[in] dos Pointer to a OutputStream object.

Return values:

void

Implements Expression.

Definition at line 78 of file varstepcondexpression.cpp.

References econd, and var.

void VarstepCondExpression::replaceVarId	(	unsigned	old_id,
		unsigned	new_id
	)			`[virtual]`

Replaces all matching variable IDs by a new one.

Replaces all matching variable IDs by a new one, which is needed in case of calling method rewriteVarsteps().

Parameters:

`[in]`	old_id	Old variable ID.
`[in]`	new_id	New variable ID, which should be introduced instead.

Return values:

void

Reimplemented from Expression.

Definition at line 59 of file varstepcondexpression.cpp.

References VarExpression::replaceVarId(), var, and varstep.

void VarstepCondExpression::rewriteVarstepCondExps ( ) [virtual]

Rewrites all if($x) if-conditions into equivalent if(fn:not(fn:empty($x))) XQuery expressions.

Return values:

void

Reimplemented from Expression.

Definition at line 72 of file varstepcondexpression.cpp.

References econd, Expression::setType(), var, and varstep.

void VarstepCondExpression::scopeCheck	(	vector< unsigned > &	def_vars,
		vector< unsigned > &	introduced_vars,
		vector< unsigned > &	violating_vars
	)			`[virtual]`

Returns if all used variables were previously (through a for-clause) defined or if a variable leaves their defined scope.

Parameters:

`[in]`	def_vars	Vector containing all previously defined variables.
`[in]`	introduced_vars	Vector containing all up to this expression defined variables.
`[in]`	violating_vars	Vector containing all variables which violates the scope condition.

Return values:

void

Reimplemented from Expression.

Definition at line 49 of file varstepcondexpression.cpp.

References VarExpression::scopeCheck(), var, and varstep.

Member Data Documentation

ExistsCondExpression * VarstepCondExpression::econd [private]

The rewritten ExistsCondExpression of the entered VarExpression or VarStepExpression.

The rewritten ExistsCondExpression of the entered VarExpression or VarStepExpression after calling method rewriteVarstepCondExps(). This member variable is NULL on creation of object but should not be NULL anymore after method rewriteVarstepCondExps() has been executed.

Definition at line 136 of file varstepcondexpression.h.

Referenced by evalCond(), extractDependencies(), init(), print(), rewriteVarstepCondExps(), and ~VarstepCondExpression().

VarExpression * VarstepCondExpression::var [private]

The entered VarExpression.

The entered VarExpression, which is the argument of the constructor. This member variable is NULL if the constructor was called with a VarStepExpression.

Definition at line 120 of file varstepcondexpression.h.

Referenced by print(), replaceVarId(), rewriteVarstepCondExps(), and scopeCheck().

VarStepExpression * VarstepCondExpression::varstep [private]

The entered VarStepExpression.

The entered VarStepExpression, which is the argument of the constructor. This member variable is NULL if the constructor was called with a VarExpression.

Definition at line 127 of file varstepcondexpression.h.

Referenced by replaceVarId(), rewriteVarstepCondExps(), and scopeCheck().


Public Member Functions
	VarstepCondExpression (VarExpression *_var)
	Constructor.
	VarstepCondExpression (VarStepExpression *_varstep)
	Constructor.
virtual	~VarstepCondExpression ()
virtual void	scopeCheck (vector< unsigned > &def_vars, vector< unsigned > &introduced_vars, vector< unsigned > &violating_vars)
virtual void	replaceVarId (unsigned old_id, unsigned new_id)
virtual void	extractDependencies (vector< DependencySet * > *depset)
void	rewriteVarstepCondExps ()
virtual void	print (OutputStream &dos) const
virtual void	init (BufferNode *root)
virtual bool	evalCond (OutputStream &eos, Environment *env, unsigned modus)
Private Attributes
VarExpression *	var
	The entered VarExpression.
VarStepExpression *	varstep
	The entered VarStepExpression.
ExistsCondExpression *	econd
	The rewritten ExistsCondExpression of the entered VarExpression or VarStepExpression.